Method of and apparatus for spinning



@ch 15, 1935. w. WHITEHEAD METHOD OF AND APPARATUS FOR SPINNING Filed Jan. 1,

INVENTOR WiHio m Whireheud ATTORNEYS Patented Oct. 15, 1935 UNlTE'D ST-TES OFFlCE SPI William Whitehead, Cumberland, Md., assignor to Celanese Corporation of America, a' corporation of Delaware Application January 21, 1929, Serial No. 333,844

7 Claims.

This invention relates to method of and apparatus for the manufacture of artificial filaments, such as yarns, bristles and the like, and relates more particularly to those methods wherein a solution of a derivative of cellulose in a volatile solvent is extruded through orifices into a heated evaporative atmosphere, which methods are known as dry spinning.

An object of my invention is to obtain artificial filaments or yarns containing organic derivatives of cellulose that have more uniform lustre than those previously made.

A further object of my invention is to provide process of and apparatus for the dry spinning of artificial filaments of solutions of derivatives of cellulose in volatile solvents, wherein convection currents in the dry evaporative atmosphere are materially reduced.

A further object of my invention is to provide process of and apparatus for dry spinning of artificial filaments from solutions of derivatives of cellulose in volatile solvents, wherein the crosssectional area of the space wherein the threads of the solution of the derivative of cellulose are subjected to the action of the heated evaporative atmosphere is materially reduced, thus increasing the speed of flow of the evaporative atmosphere. Other objects of my invention will appear from the following detailed description.

In the methods heretofore employed for the dry spinning of artificial yarn from solutions of derivatives of cellulose in volatile solvents, such solutions are forced through the orifices of a spinneret into a spinning unit through which a heated evaporative atmosphere flows. These spinning units are of comparatively large crosssectional area, of 1 square foot or more.

The prior methodsdo not produce yarns of as uniform lustre or other physical properties as may be desired. I have found that this is due to the fact that because of the comparatively large cross-sectional area of the spinning unit or cell, convection currents are set up by radiation losses and/or evaporation of the solvent from the spinning solution, and that these convection currents cause variations in the temperature and the amount of solvent vapors contained in the drying atmosphere in the zone where evaporation of the volatile solvent from the solution is caused. I have further found that the variation in the degree of saturation of the drying atmosphere causes variation in the lustre of the filaments or yarns-that are produced. When spinning is performed in a drying atmosphere having a high concentration of solvent vapors, filaments of high lustre are produced; while spinning in a drying atmosphere of low concentration of solvent vapors produces filaments or yarns of low lustre. Thus if convection currents cause drying atmospheres of varying concentration of solvent to 5 come in contact with the spinning solution as it leaves the spinning jet, yarns or filaments of varying lustre will be formed. This variation also causes unevenness of pliability of the yarn.

I have found that if the cross-sectional area of 10 the spinning unit is reduced to or less of that of the spinning units previously employed, yarns or filaments of more uniform lustre or other properties may be produced.

In accordance with my invention I prepare 5 artificial filaments from solutions of organic derivatives of cellulose, for instance, in a suitable volatile solvent by extruding the same through the orifices of a spinning jet into a heated evaporative atmosphere contained in a spinning unit 20 of reduced cross-section. The filaments or yarns thus formed are then drawn off and wound onto a winding machine running at a uniform rate, Which Winding machine may also impart twist to the filament, if desired. The filaments or 25 yarns thus formed are of a high and uniform lustre and have other desirable uniform optical and physical properties. 1

Any suitable artificial filaments or yarns may be produced by my invention. The filaments 30 may be fine, say having deniers of less than 2 to 10 or more, to be used as such, or to be associated together to form yarns of various size. Heavier filaments having deniers of 20 to 500 or more may 35 also be made to be used as artificial bristles for brushes or artificial fur. Bands or ribbons may also be made by my invention to be used in v making braids or as artificial'straw.

Any suitable derivative of cellulose such as or- 40 ganic derivatives of cellulose may be employed which may be organic esters of cellulose and cellulose ethers. Examples of organic esters of cellulose are cellulose acetate, cellulose formate, cellulose propionate and cellulose butyrate, while 45 examples of cellulose ethers are ethyl cellulose, methyl cellulose and benzyl cellulose. Solutions of cellulose nitrate may also be spun in this manner, and if desired, the cellulose nitrate filaments or yarns may then be denitrated in any suitable 5O manner. I

Any suitable solvent may be employed examples of which are acetone, mixtures of chloroform and ethyl alcohol or methyl alcohol, ethylene dichloride, methylene chloride or ether and alcohol, or 55 other suitable solvents or suitable mixtures of these.

As stated, the spinning unit into which the threads of the solution of the derivative of cellulose are extruded and through which a heated evaporative atmosphere fiows, should be of reduced cross-section of A; or less of that heretofore employed.

Thus, the horizontalcross-section of the spinning unit or cell may be 12" x 4'', (48 square inches) or 12" x 2", (24 square inches) especial ly if a plurality of spinning units, say" four or' more, are employed in one cabinet. The spinning units may be further reduced in size solthat they have a cross-section of 2" x 6", (12 square inches), 3 x 6", (18 square inches), or 4 x 6", (24 square inches) especially in those cases where only two spinning units are employed in one cabinet. The size of the spinning unit may beefurther reduced so that it has a cross-sectional area of only 2" x 3", (6 square inches) or 3" x 3", (9 square inches), especially in cases where only one spinning unit is employed in the cabinet.

The evaporative'atmosphere employed for volatilizing the solvent from the spinning solution may be any appropriate gas, such as air, hydrogen or a gas that does not support combustion such as nitrogen, carbon dioxide, etc. The evaporative atmosphere may be heated in any suitable manner, such as by heating coils or heating elements placed along the vertical walls of the spinning unit or cell. However, because of the restricted cross-section of the spinning unit, such coils or elements on the walls may tend to obstruct free passage of the artificial filaments or threads therethru. Therefore, I prefer to place heating coils or elements in the base of the spinning unit or else to preheat the evaporative atmosphere in a heater before it enters the spinning chamber, or both of these expedients may be employed, thus avoiding close proximity of the heating elements with the vertical walls of the spinning unit. Less desirably, the vertical walls of the spinning chamber may be'jacketed and heating means such as steam may pass therethru, or electrical resistances may be placed therein.

In order further to explain my invention, reference is had to the accompanying drawing, wherein Figure 1 is a vertical cross-section of a cabinet having four spinning units constructed in accordance withmy invention.

Figure 2 is a cross-section along line 2-2, and

Figure 3 is a vertical cross-section of a modification embodying my invention.

Referring to Figures 1 and 2,- the' walls of the spinning unit areindicated at I and are preferably lagged withheat'insulating material. The space within these walls have a cross-sectional area substantially the same as that of spinning units heretofore employed, and therefore in order to restrict the. effective cross-section of the dry ing zone, I provide the baffles 2 which define drying zone 3.

The spinning solution is introduced by the pipe t to the pump 5, which supplies a practically uniform amount of spinning solution per unit of time to the pipe 6 which leads to a candle that contains a filtering medium, in order to filter out any trace of solid impurities that may be present in the spinning solution. The spinning solution fromtthe' candle 1 passes to the metal cap or jet Shaving a number of holes or orifices of required suitable winding device (not shown).

the orifices of the jet 8, the fine threads of spinning solution lose at least part of their volatile solvents as vapors, and assume the form of tough filaments or threads 9 of predetermined size. These filaments pass under the guide roller l8 around the rotating roller H and pass to any If desired, 10 this winding device may also twist the filaments into a single thread and may be in the form of a cap spinning device.

To causeevaporation of the volatile solvent contained in the spinning solution extruded through" the orifices of the jet 6, a heated gas such as air, nitrogen, carbon dioxide or hydrogen is caused to fiow up through the spinning unit.

The gas may be heated prior to entry in the base of the spinning unit or the air may be heated by steam coils E3 in the base I 2 of the spinning unitj If'desired, both of these methods of heatingthe evaporative gas may also be employed. The evaporative gas may be forced into the base of the spinning unit or it may be drawn upv through the same by suction supplied to the exhaust pipe M which is preferably supplied with a perforated cap l5, entry of the evaporative gas being effected by means of openings 56 in thebases of the spinning units.

To permit inspection of the interior of the cabinet, glass windows 5 are provided in the walls 4; and to permit access to the interior the doors H are provided.

In the modification shown in Figure 3, a spinning unit of restricted cross-sectional area is made by the walls 28 of the unit itself instead of having partitions provided inspinning units of standard size to restrict the cross-sectional area thereof as shown in Figures 1 and 2. Otherwise 40,

the unit shown'in Figure 3 is the same as that shown in Figures 1 and 2.

It will be thus seen that by my invention, the passage through which the drying evaporative atmosphere passes in contact with the artificial filaments or threads under formation is greatly restricted. This restriction causes amuch greater linear velocity'of gases and vapors for the given volume of evaporative gas that is necessary to effect suitable drying of the filaments under formation. These factors cause great decrease of convection currents, and prevent periodic changes of saturation of solvent vapors around the critical zone of drying of the filaments, and

as a result thereof, filaments or yarns having a much greater uniformity with respect to luster, other optical or physical properties and affinity to dyes, both along the length of the same yarn and with respect to other yarns, are obtained.

It is to be understood thatthe foregoing deso tailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of my invention.

Having describedmy invention what I claim and desire to obtain by Letters Patent is:

1. Method of forming artificial filaments of substantially uniform properties, which comprises extruding a solution of an organic derivative of cellulose in a volatile solvent through orifices immediately into a column of heated evaporative medium having a cross-section not substantially greater than the area occupied by the group of extruded filaments.

2. Method of forming artificial filaments of substantially uniform properties, which comprises extruding a solution of cellulose acetate in a volatile solvent through orifices immediately into a column of heated evaporative medium having a cross-section not substantially greater than the area occupied by the group of extruded filaments.

3. In a device for spinning artificial filaments, the combination of a spinning unit comprising a spinning chamber, a jet through which a solution of a derivative of cellulose is adapted to be extruded in the form of filaments extending into and located within said spinning chamber, the cross-section of said spinning chamber being not substantially greater than the area of the jet, means for causing heated gas to pass through said spinning unit and means for drawing oil the filaments.

4. In a device for spinning artificialfilaments, the combination of a spinning unit comprising a spinning chamber, a jet through which a solution of a derivative of cellulose is adapted to be extruded in the form of filaments extending into and located Within said spinning chamber, the cross-section of said spinning chamber being not substantially greater than the area of the jet, a heating element in the base of said spinning unit, means for causing a gas to fiow in contact with said heating element and then through the spinning unit and means for drawing off the filaments.

5. In a device for spinning artificial filaments, the combination of a spinning unit comprising a spinning chamber, a jet through which a solution of a derivative of cellulose is adapted to be extruded in the form of filaments extending into and located within said spinning chamber, the cross-section of said spinning chamber being not substantially greater than the area of the jet, 5

means for causing heated gas to pass through said spinning unit and means for drawing ofi the filaments at a point along the length of said spinning chamber.

6. Method of forming artificial filaments of substantially uniform properties, which comprises extruding a solution of an organic derivative of cellulose in a volatile solvent through orifices immediately into a column of heated evaporative medium having a cross-section not substantially greater than the area occupied by the group of extruded filaments and withdrawing the filaments at a point intermediate the extremities of said column of heated evaporative medium.

'7. In a device for spinning artificial filaments, the combination of a spinning unit comprising a spinning chamber, walls surrounding said spinning chamber to form a jacket around the same, a jet through which a solution of a derivative of cellulose is adapted to be extruded in the form of filaments extending into and located within said spinning chamber, thecross-section of said spinning chamber being not substantially greater than the area of the jet, means for causing heated gas to pass through said spinning unit and means for drawing ofi the filaments.

WILLIAM WHITEHEAD. 

